Surface-free energy and bacterial adhesion. An in vivo study in beagle dogs

Conflicting reports have been presented on the rôle of substratum surface free energy (s.f.e.) on bacterial adherence. It is the aim of the present study to evaluate the effect of the s.f.e. of substrata on bacterial adherence in vivo. The following substrata with s.f.e. varying from 23.3-124.9 erg X cm-2 were cut into facings of 5 by 6 mm, polished and cleaned: polytetrafluorethylene (PTFE), Parafilm, polyvinylchloride (PVC), polymethylmethacrylate (PMMA), bovine dentin, bovine enamel and glass. In 5 beagle dogs, 7-9 years old, part of the buccal periodontium of the upper cuspids was excised and crowns were made and cemented with a non-fluoridated cement. The facings were placed in the crowns and placed in the oral cavity for 2 h. After removal, the facings were rinsed in saline. S.f.e. was assessed from contact angles with water, water/n-propanol mixtures and a-bromonaphthalene, according to the concept of dispersion and polar components, firstly on clean air dried facings and later on facings exposed to the oral cavity for 2 h. Immediately after rinsing, the water contact angle was measured as a function of time, to monitor the evaporation of free water from the protein layer adsorbed on the substrate which had been exposed to the oral cavity. It appeared that after a rapid increase in contact angle, a stable maximum value was obtained after 40-120 min depending on the substratum. S.f.e.'s of the protein-coated substrata were subsequently determined after a 120 min drying period. Following the contact angle determinations, the exposed facings were stained with ethidium bromide, enabling fluorescence microscopical counting of the adhered microorganisms.(ABSTRACT TRUNCATED AT 250 WORDS)